style: Part 1: Add SVG d property in CSS

Add d property for style system. d property only supports path() for now
and it has the functional notation without fill rule.

https://github.com/w3c/svgwg/issues/320#issuecomment-414462645

Differential Revision: https://phabricator.services.mozilla.com/D81237

components/style/properties/counted_unknown_properties.py

@@ -63,7 +63,6 @@ COUNTED_UNKNOWN_PROPERTIES = [
     "-webkit-text-combine",
     "-webkit-text-emphasis-style",
     "-webkit-text-emphasis",
-    "d",
     "-webkit-mask-box-image-width",
     "-webkit-mask-box-image-source",
     "-webkit-mask-box-image-outset",

components/style/properties/longhands/svg.mako.rs

@@ -246,3 +246,13 @@ ${helpers.predefined_type(
     animation_value_type="LengthPercentage",
     spec="https://svgwg.org/svg2-draft/geometry.html#R",
 )}
+
+${helpers.predefined_type(
+    "d",
+    "DProperty",
+    "specified::DProperty::none()",
+    engines="gecko",
+    animation_value_type="ComputedValue",
+    gecko_pref="layout.css.d-property.enabled",
+    spec="https://svgwg.org/svg2-draft/paths.html#TheDProperty",
+)}

components/style/values/computed/mod.rs

@@ -82,7 +82,7 @@ pub use self::position::{
 pub use self::ratio::Ratio;
 pub use self::rect::NonNegativeLengthOrNumberRect;
 pub use self::resolution::Resolution;
-pub use self::svg::MozContextProperties;
+pub use self::svg::{DProperty, MozContextProperties};
 pub use self::svg::{SVGLength, SVGOpacity, SVGPaint, SVGPaintKind};
 pub use self::svg::{SVGPaintOrder, SVGStrokeDashArray, SVGWidth};
 pub use self::text::TextUnderlinePosition;

components/style/values/computed/svg.rs

@@ -11,7 +11,7 @@ use crate::values::generics::svg as generic;
 use crate::values::RGBA;
 use crate::Zero;
 
-pub use crate::values::specified::{MozContextProperties, SVGPaintOrder};
+pub use crate::values::specified::{DProperty, MozContextProperties, SVGPaintOrder};
 
 /// Computed SVG Paint value
 pub type SVGPaint = generic::GenericSVGPaint<Color, ComputedUrl>;

components/style/values/specified/mod.rs

@@ -80,7 +80,7 @@ pub use self::position::{PositionComponent, ZIndex};
 pub use self::ratio::Ratio;
 pub use self::rect::NonNegativeLengthOrNumberRect;
 pub use self::resolution::Resolution;
-pub use self::svg::MozContextProperties;
+pub use self::svg::{DProperty, MozContextProperties};
 pub use self::svg::{SVGLength, SVGOpacity, SVGPaint};
 pub use self::svg::{SVGPaintOrder, SVGStrokeDashArray, SVGWidth};
 pub use self::svg_path::SVGPathData;

components/style/values/specified/svg.rs

@@ -10,6 +10,7 @@ use crate::values::specified::color::Color;
 use crate::values::specified::url::SpecifiedUrl;
 use crate::values::specified::AllowQuirks;
 use crate::values::specified::LengthPercentage;
+use crate::values::specified::SVGPathData;
 use crate::values::specified::{NonNegativeLengthPercentage, Opacity};
 use crate::values::CustomIdent;
 use cssparser::{Parser, Token};
@@ -334,3 +335,57 @@ impl Parse for MozContextProperties {
         })
     }
 }
+
+/// The svg d property type.
+///
+/// https://svgwg.org/svg2-draft/paths.html#TheDProperty
+#[derive(
+    Animate,
+    Clone,
+    ComputeSquaredDistance,
+    Debug,
+    Deserialize,
+    MallocSizeOf,
+    PartialEq,
+    Serialize,
+    SpecifiedValueInfo,
+    ToAnimatedZero,
+    ToComputedValue,
+    ToCss,
+    ToResolvedValue,
+    ToShmem,
+)]
+#[repr(C, u8)]
+pub enum DProperty {
+    /// Path value for path(<string>) or just a <string>.
+    #[css(function)]
+    Path(SVGPathData),
+    /// None value.
+    #[animation(error)]
+    None,
+}
+
+impl DProperty {
+    /// return none.
+    #[inline]
+    pub fn none() -> Self {
+        DProperty::None
+    }
+}
+
+impl Parse for DProperty {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        // Parse none.
+        if input.try_parse(|i| i.expect_ident_matching("none")).is_ok() {
+            return Ok(DProperty::none());
+        }
+
+        // Parse possible functions.
+        input.expect_function_matching("path")?;
+        let path_data = input.parse_nested_block(|i| SVGPathData::parse(context, i))?;
+        Ok(DProperty::Path(path_data))
+    }
+}